Lubricating oil additives comprising mixtures of polyvalent metal dithiocarbamates



No Drawing. i Filed May-9, ser.

This invention relates tok the?preparation-andfuse#oh oil additives and is particularly concerned with the preparation and use Ofmixgtures. Qtfnolryalenttmetal..dtbie;

carbamates as oil additives.

Deterioration ofthe moving parts of bearings appears to result from the formation of undesirable products in the oils which are used Eto lubricate the bearings. These undesirable products Y are caused-Y primarily by dilution andox1d at1on which tend I'to change theV viscosity of thelubricants and provide reactive chemicals which pit the surfaces Y of the `bearings.^""1l11"s` problem" is particularly acute when'-the bearings-#areniade-fromtsensitive metal alloys which may contain xtures comprised in part of cqpper, lead C asinriymr. ...silvenamlatina. Bearingw fallure 1s particularly noticeable in heavy-duty service, e.g,. the operationhrfahtrpglgubpses, ships,I planes and stationary power plants.

Many attempts. haya been.. made to.. Qvercamethe. problem of deterioration of metal bearings, but these etorts have not proved tov be completely successful. Most suchattempts have" b'ele'ni ;"inthe-nature ofaddingg;` various'chemical compositions t'o tlieffoilsswhichfarefised` to llubricate the beajriiigs. For example,,alkaline acidfmhrbltors have been added tolubricatingoils inorder to prevent the oil fromv becoming acid,""and"variusjsoamv 1i1r e materials-have been added' talons ingoraer; fofheip z removev deposited sludge. ``Inaddicion, various antif oxidants havebefen' addedin ordertom nh'ibit oxidation'ofm the oilsand thefsubseqilenf" r"ruf lp'rifff'uindsible chemicals within theilubriea't "Also, yindiX'I-izll'lal"l't'olyirle': g g *dithiocarbarnatesfare known to be useful oil additivesbecis'tlieyfsei'vthe dual function of sequesteriggglpkdesirable metal components of the oilA and because theyfunction asian, tioxidantslv Thepractice has developed of adding individualwpolyf.. valent metal dithiocarbamates toflubratjfffil form of compatibleoil,concentrates- Ilhese comp` oil concentrates areumuch .easie'r :and:,in'lore' convenient to add'v to the lubricating oils than-'the pure powdered dithiocarbamates 'because "th'elatterj' must; b'ej processed" vintoj the joil 'by' irieans'fof iheatingglfstir'rlin andiil'teririg. It`y is," therefore;Y economically# imperativethat-the lconi centration ofpolyvalent metal dithiocarbamatesf'in-"the compatible oilsv be as-high'y as-poss'iblebutlow enough toV prevent crystallization f. thea` dithioc'arbamates duri 'g' t ..11 i t, j r-,ult Because the polyvalent m-e'tal ions i'n -thef dithio-A carbamates 'arethe electfv'; components'offthe additives; it is desirable that the concentrate contain a maximum concentration of polyvalent metal dithiocarbarnates which are*v comprised #of the l lowest .possible`vr effective molecular-weights. 'f

v" It is afgene'ral'object ofIthisffinvention..tofprepare.improved polyvalent metal dithiocarbamate:oil'iadditives. It is another object ofifthis invention to prepare mixtures comprised of at least; twopolyvalent metal dithiocarbamates. It is a further object of this invention to prepare mixtures comprised of at least two polyvalent metal carbamates.- `When themlxturellswcomprised, ofvm1xtures 2,947,695 RatentedAagf .2 1360 dithiocarbamates which have improved solubilities in oils. It is another'object ofth'is invention to prepare carbb It has ,been,discoveredthatthe concentration of polyvalent metal dithiocarbamates vin, compatible oils can be increasedLudt-hout the'. danser 0f. crystallization Whnythe dithiocarbamates are'mixtui'es comprisedl ofat-leasttwof pelyvalentmataldithiqarbamates- "These jmixturescan belrdescribed as Vtuije'of at least two dithioc'arbarr'latesr ofjtheseneral'fermqlaf 1Q R7," si( si N-cliifshx-Y-s-ii-.N .Y j f \'R,fl wher/Qin. Xfais apelyyalent metal. and `wherein-tire:Ris are; SQIeCteQIrQmthe greunfconsistnat aliphatic radicals, cy@ .Qalphata radicals, .aralkylradicals, wclgalplsac, rings formed by the joiningtogetherof the-pairgofks on;a nitrogen, atomanllheterocyclic rings formed byfthe joining togethenof thepair ofiRs 'ona nitrogen atom. e polyvalent metals whichare useful in thepractice S invention. are. rgeneral ly selectedfrlornthe groupg. @asistan-0f Zinc, ferric. iron., l barium, .magneSium,- cal? cium, strontium and radium. The mixedzinc ditltrio -y carbamateslconstitute a,preferred.class'ofadditivesv Y. dithi rbanlates ;Whi..h= amused .in .the Pftceto, thieme] op arettgixturesfef meer:mgefldlerenfid' 5 thilocai-bamat wher'ei Vallot theradicals attached. to.; a@ ermita f the mixture which contains 1.0 to 1.5...Amolesfofsodiunajdimfoutyl dithiocarbamate, 0.1 to n05, 112912 of sodium diethyl di'- thiocarbamate, 0.1 to 0.5 mole of sodium diamyl dithiocarbamate'andOS-to '0.2" mole of sodium diisopropyl dithiocarbamate which is precipitated by the addition of onelf-,halffthe number of moles of Va soluble zinc salt as there are total moles of the sodium salts. However, the percentages; ofthe mixtures may vary considerably, the only requirementbeing v that -aY-nrixtu,reI be lcomprised of atfleast two polyvalent rnetal dithiocarbamateswhich aref'. present in substantial proportions, the proportions being` svuicient toincrease thesolubility ofthe mixture in oil. over the. solubilitiestof .the individual components,V of `the. mixture.r Normally each component will be present in a proportioned atleast-,Szfbyweight, basednltherfweight 1 OfethmSl-Ut I The concentrations of mixtures of polyvalentmetal dil-V thiecanbamates inthe Vcompati-l?le Oils Willwaryonsiderably However... .the cencentra-ton; will normally, range'. from.;21l.1 ..1.1t.L 5% byaweieht-.Qft polyvalent: metal; dithigr., caroamates, based on the weight of the oil-dithiocarbarn ates solution, to byAJvYeightlfand will Vary depending upon the composition of the mixture of dithio of zincrldithiocarbamatesin compatible oils, the concen-A tra-tionfsgofy effective I=zinc-ii1|tl`1e oilcarrier will v`be atv lleast 13%: by'wcight of Zincbased on the weight ofthe mixe tureofzinc; dithiocarbamates. In this form', the oili` concentrates can be added tocustomary lubricatingoilsin the most eiective proportions.

`The mixtures of dithiocarbamates may also be described as mixtures of at least two dithiocarbamates havv valent metal dithiocarbamates with a soluble polyvalent metal salt and thereby precipitating the `-mixture of polyvalent metal dithiocarbamates. The `soluble sulfates, nitrates and chlorides may be used for the purpose, although other soluble salts are satisfactory. Mixtures of` polyvalent metal dithiocarbamates may also be obtained by combination of two or more individually prepared polyvalent metal dithiocarbamates.

These mixtures may also be prepared hy mixing the amines before reacting with a strong monovalent metalY alkali (such as sodium hydroxide) and carbon disulfide in an aqueous solution. Reaction with one or more polyvalent metal salts produces the mixture of polyvalent metal dithiocarbamates.

The mixtures of dithiocarbamates are thereafter added to an oil, which is compatible with the customary lubricating oils, in lthe highest possible concentration. This concentration will customarily range from about by weight to about 50% by weight based on the weight of the compatible oil-dithiocarbamates solution.

` Tests have been made to illustrate that mixtures of polyvalent metal dithiocarbamates are more soluble in organic liquids, such as oils, than are the pure components. A hydrocarbon solvent was prepared by mixing together equal volumes of benzene and n-hexane. The solubililties of various zinc dithiocarbamates and mixtures of zinc dithiocarbamates are shown in Table I. The test solutions were prepared by saturating the solutions with the indicated components at 40 C. and thereafter allowing the solutions to reach equilibrium by allowing them to cool to routine temperature.l

Thus, it is quite apparent that mixtures are considerably more soluble in organic solvents than are the pure compounds and that the more complex the mixture the greater the solubility.

The preparation of mixed polyvalent metal dithiocarbamates is illustrated by the following examples which are not intended as limitations on the scope of the invention.

, Example] Y V A solution containing 60 milliliters of a l molar sodi; um di-n-butyl dithiocarbamatesolution, milliliters ofa 1 molar sodium' diisopropyl dithiocarbamate' solution and: 20 milliliters of a l molar sodium diethyl dithiocarbamate solution was prepared. This solution was their slowlyadded to a solution of 14.4 grams 'of ZnSO'4.7H3O` 4, in 200 milliliters of water. The resultant precipitate was filtered, washed with water and dried. It was ground to a ne white powder which weighed 20.0 grams.

Example 2 A solution containing 15.1 milliliters of a 1 molar sodium (mixed)di-amyl dithiocarbamate solution, 54.0

milliliters of a l molar sodium di-n-butyl dithiocarbam' atesolution, 4.8 milliliters of a l molar sodium diisopropyl dithiocarbamate solution and 16.9 milliliters of a 1 molar sodium diethyl dithiocarbamate solution was prepared. This solution was then slowly added to a solution of 13.1 grams of ZnSO4.7H2O in 200 milliliters of water. The resultant precipitate was filtered, washed with wateranddriedl It was ground to a ne white powder which weighed 19.5 grams.

Various solutions of polyvalent metal dithiocarbamates in oils were prepared. The oils were petroleum hydrocarbon oils as sh'own in Table II. f

TABLE II Flash Point Y Viscosity at;

Cleveland F. 011 Open Cup, Saybolt F. Universal,

sec.

The following oil concentrates were prepared:

These oil concentrates were set aside for a period of four weeks after which they were tested for opaqueness, to wit, whether or not crystallization had occurred. These results are listed in Table IV.

TABLE IV solutions v1 2 a 4 s i e an o a ue translutrauslutranslutranslu- App ar 1Jalilnost cent. cent. cent. cent.

solid.

Thus, it is shown that mixtures do not tend to crystallize out of organic solvents, such as oils, as readily as pure compounds.V

While certain representative embodiments and details Ihave been shown for the purpose of illustrating the invention, it wil be apparent to those skilled in this art that various changes and' modiiications may be made therein without departing from the Spirit or scope of the invention.` l

1. A lubricating oil additive 'composition consisting of a petroleum hydrocarbon lubricating oil solution of a mixture of at least two diierent dithiocarbamates ofthe general formula:

wherein X is a polyvalent metal selected from the group consisting of zinc, ferrie iron, barium, magnesium, calcium, strontium and radium and R, R1, R2 and R3 are aliphatic radicals having from 1 to 5 carbon atoms, and wherein the average number of carbon -atoms in 0.1 to 0.5 mole of sodium diethyl dithiocar'oamate, 0.1 t 0.5 mole of sodium diamyl dithiocarbamate and 0.05 to 0.2 mole of sodium diisopropyl ditbiocarbamate which is precipitated by the addition of one half the number of moles of a soluble zinc salt as there are total moles of the sodium salts.

References Cited in the file of this patent UNITED STATES PATENTS 2,046,884 Semon July 7, 1938 2,265,851 Matheson Dec. 9, 1941 2,394,536 Denison et al Feb. 12, 1946 2,614,987 Dreher et al Oct. 21, 1952 2,747,978 Closson et al May 29, 1956 FOREIGN PATENTS 660,355 Great Britain Nov. 7, 1951 

1. A LUBRICATING OIL ADDITIVE COMPOSITION CONSISTING OF A PETROLEUM HYDROCARBON LUBRICATING OIL SOLUTION OF A MIXTURE OF AT LEAST TWO DIFFERENT DITHIOCARBAMATES OF THE GENERAL FORMULA: 